The human eye functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of a crystalline lens onto a retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and the lens.
When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. An accepted treatment for this condition is surgical removal of the lens and replacement of the lens function by an artificial intraocular lens (IOL).
In the United States, the majority of cataractous lenses are removed by a surgical technique called phacoemulsification. During this procedure, an opening is made in the anterior capsule and a thin phacoemulsification cutting tip is inserted into the diseased lens and vibrated ultrasonically. The vibrating cutting tip liquefies or emulsifies the lens so that the lens may be aspirated out of the eye. The diseased lens, once removed, is replaced by an artificial lens.
The IOL is injected into the eye through the same small incision used to remove the diseased lens. The IOL is placed in an IOL injector in a folded state. The tip of the IOL injector is inserted into the incision, and the lens is delivered into the eye.
Many IOLs manufactured today are made from a polymer with specific characteristics. These characteristics allow the lens to be folded, and when delivered into the eye, allow the lens to unfold into the proper shape. The polymers used to make these lenses have characteristics that are temperature-dependant. Heating the polymer allows the IOL to be compressed more easily, thus allowing it to fit through a smaller incision. A smaller incision is desirable because it promotes faster healing and is less traumatic for the patient.
The temperature characteristics of the polymers used to make IOLs can impact the lens implantation process significantly. For some polymers, a change in hardness or viscosity occurs over a relatively narrow range. For example, at colder temperatures, the polymer may become brittle and break if folded. At higher temperatures, the polymer may become gooey and lose its shape retaining ability. Therefore, it is desirable to maintain the polymer in a specific temperature range so that the IOL can maintain its integrity.
In practice, some surgeons have manually heated IOLs using the outside of autoclaves or warmers designed to warm baby wipes. Such warming is uncontrolled. As noted, the polymers used to manufacture artificial lenses are sensitive to temperature, and more precise temperature control can achieve desired results.
Therefore, a need exists for a temperate-controlled intraocular lens injection device.